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Důkazem vysokého vzdělání je schopnost mluvit o největších věcech nejjednodušším způsobem.

David Hume

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?-Fe2O3 Nanoparticles Covered with Glutathione-Modified Quantum Dots as a Fluorescent Nanotransporter

Over the past decade, magnetism and magnets have found a growing field of application in the areas of biotechnology and medical technology. Combining the forces of magnetism with micro- and nanotechnology has further miniaturized the modes of application [1]. Examples of applications are ranging from magnetoresistive-based biosensors, visualization of common biological events, to nanomedicine [2-4]. Maghemite (?-Fe2O3) is iron oxide, able to form particles smaller than 10 nm showing superparamagnetic and paramagnetic properties at room temperature [5]. The possibilities of iron oxide nanoparticles have markedly increased due to the versatile characteristics of these materials arising from the ability to manipulate and control their surface functionalities, and thus to form potentially novel material with wide range of applications. One big advantage of iron oxide nanoparticles is their biocompatibility and low toxicity vertebrates [6, 7], predestining nanomaghemite to enhance the theranostic possibilities. Within the medical field, nanomaghemite has been studied widely to enhance cancer treatment, and diagnostic techniques, such as drug delivery systems [8-10], photoabsorbers in photodynamic therapies [11, 12], hyperthermia in cancer therapies [13-15], and magnetic resonance imaging (MRI) contrast agent carriers [16-18].

Nanoparticles like maghemite, as well as carbon nanotubes, and others lack fluorescent properties sufficient to monitor their optical transport in vitro or in vivo, limiting the study of their transport [19]. Even though gadolinium has been used to enhance contrast of iron oxide nanoparticles by Kim and colleagues, and they demonstrated the potential of iron oxide nanoparticles as T1 MRI contrast agents in clinical settings [20], only few attempts have been made to optically track nanomaghemite interaction in eukaryotic cells [21, 22]. Employment of quantum dots as labels offers numerous advantages, as they are resistant to both photo- and chemical degradation over time, and they provide a wide excitation band with a narrow emission band [23]. Furthermore they exhibit pronounced brightness compared to other fluorophores. A lot of studies have been aimed at determination of both in vitro and in vivo toxicity of these nanoparticles and the results are promising to use these nanomaterials in vivo. There was shown that QDs toxicity is highly dependent on QDs crystal size, stability in solution, as well as physical environment [24-26], however, the using of properly prepared and modified QDs had negligible toxicity. Moreover, these particles can be conjugated to other materials as they were successfully conjugated to maghemite nanoparticles through covalent binding [27], or using binders like 3- aminopropyltrimethoxysilane (APTES) [28]. Generally, in core-shell QDs such as ZnSe/CdS or CdTe/CdS the shell material is grown onto the core material to reduce the nonradiative recombination effectively by confining the wave function of an electron-hole pair to the interior of core material [29, 30]. Such core-shell particles display efficient luminescence with stability superior to single phase nanoparticles and organic dyes and are of great interest for biological imaging and light-emitting devices [31]. The aim of this study was to synthesize and characterize the nanoconjugate of maghemite nanoparticles conjugated to CdTe/CdS QDs stabilized with glutathione (GSH), whose could be subsequently applied on the human embryonic kidney 293 cell culture (HEK-293) to monitor the possible interactions between luminescent nanomaghemite and eukaryotic cells. We hypothesized that thiol groups contained in glutathione may provide interaction with cell membranes, and thereby to functionalize maghemite nanoparticles to be able to serve as a tool for transport of drugs targeting the structures on outer surface of the cell membranes. Moreover; the adsorption of cells on surface of conjugate can be utilized for separation of cells from medium.

Práce je spojená s projektem CEITEC CZ.1.05/1.1.00/02.0068.

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